Abstract

Prawns being demersal in habit, occur rarely in purse seine catches. A study of prawns occurring in purse seine catches in Cochin and Karnataka region ,and also the comparison of its size composition has been attempted. The occurrence of M. dobsoni in appreciable quantities in the purse seines has been noted. Aa at Cochin M. dobsoni contributed to the bulk of the heavy catch, 98.3% and 93.3% respectively at Mangalore and Malpe. The rest of the catches constituted Penaeus indicus. When there was very high catch M. dobsoni formed almost 100% of the landings. More or less the same ratio of sex distribution as at Cochin was noticed at both Mangalore and Malpe, the female to male ratio being 56:44. In comparison to the sizes landed at Cochin during the pre-monsoon period the sizes occurring in the purse seines at Mangalore and Malpe were much higher. The modal sizes of the prawns in the catches of both purse seine and trawl net in males as well as females are exactly the same in both centres, although the trawl catches at Maipe shows a much wider range in sizes when compared to the purse seine catches. The modal sizes of both males and females are much higher than that in the catches at Cochin . The females show a higher modal length in purse seine catches while males show a lower modal length, when compared to trawl catches. The dominance of females in the purse seine catches of this coast along with the fact that majority of them were in spent/spent recovering stages would strengthen the point that the behaviour of the shoals moving up in the column of water is probably related with their spawning activities. Uit can be concluded that a close monitoring of purse seine catch is essential to see that it does not affect the coastal trawl fishery that depends mainly on the penaeid prawn resources.